Publications by authors named "Zhien Wang"

15 Publications

  • Page 1 of 1

Electrochemical Delamination of Ultralarge Few-Layer Black Phosphorus with a Hydrogen-Free Intercalation Mechanism.

Adv Mater 2021 Jan 27;33(1):e2005815. Epub 2020 Nov 27.

College of Chemistry and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang, 050018, China.

Due to strong interlayer interaction and ease of oxidation issues of black phosphorus (BP), the domain size of artificial synthesized few-layer black phosphorus (FL-BP) crystals is often below 10 µm, which extremely limits its further applications in large-area thin-film devices and integrated circuits. Herein, a hydrogen-free electrochemical delamination strategy through weak Lewis acid intercalation enabled exfoliation is developed to produce ultralarge FL-BP single-crystalline domains with high quality. The interaction between the weak Lewis acid tetra-n-butylammonium acetate (CH COOTBA) and P atoms promotes the average domain size of FL-BP crystal up to 77.6 ± 15.0 µm and the largest domain size is found to be as large as 119 µm. The presence of H and H O is found to sharply decrease the size of as-exfoliated FL-BP flakes. The electronic transport measurements show that the delaminated FL-BP crystals exhibit a high hole mobility of 76 cm V s and an on/off ratio of 10 at 298 K. A broadband photoresponse from 532 to 1850 nm with ultrahigh responsivity is achieved. This work provides a scalable, simple, and low-cost approach for large-area BP films that meet industrial requirements for nanodevices applications.
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http://dx.doi.org/10.1002/adma.202005815DOI Listing
January 2021

Highly reusable nanoporous silver sheet for sensitive SERS detection of pesticides.

Analyst 2020 Aug 7;145(15):5158-5165. Epub 2020 Jul 7.

HKUST-Shenzhen Research Institute, No. 9 Yuexing first RD, Hi-tech Park, Nanshan, Shenzhen 518057, China.

Surface-enhanced Raman spectroscopy (SERS) enables pesticide detection at the point-of-need, but its practical application is limited by expensive and disposable SERS substrates. Here, we report a reusable nanoporous silver (NPAg) sheet for the SERS detection of organochlorine pesticides, aiming to maximize the cost-efficiency of substrate regeneration. The NPAg sheet is prepared by a reduction-induced decomposition method without chemical induced random aggregations. This SERS substrate is sensitive to various analytes regardless of their affinity to a metal surface such as rhodamine B, dichlorodiphenyl-trichloroethane (DDT), and lindane due to its large surface area and the coral rock-like morphology. The SERS signal of lindane, a typical organochlorine pesticide, is identified and quantified with a minimum detectable concentration of 3 × 10 M (87 ppb), which is below the maximum residue limits in various foods set by the regulators across the world. More importantly, after a few minutes of ultrasonic cleaning in water, the NPAg sheet can be reused at least 20 times with a reproducible SERS activity. Furthermore, the NPAg sheet remains stable in terms of its sensitivity and reusability after several months of bare strorage. Therefore, the NPAg sheet as a SERS substrate holds great promise for mass production and convenient applications in low-cost pesticide analysis.
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http://dx.doi.org/10.1039/d0an00999gDOI Listing
August 2020

Modeling Dust in East Asia by CESM and Sources of Biases.

J Geophys Res Atmos 2019 Jul 13;124(14):8043-8064. Epub 2019 Jul 13.

NASA Goddard Space Flight Center, Greenbelt, MD, USA.

East Asian dust has a significant impact on regional and global climate. In this study, we evaluate the spatial distributions and temporal variations of dust extinction profiles and dust optical depth (DOD) over East Asia simulated from the Community Earth System Model (CESM) with satellite retrievals from Luo et al. (2015a, 2015b) (L15), Yu et al. (2015) (Y15), and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) level 3 (CAL-L3) products. Both L15 and Y15 are based on CALIPSO products but use different algorithms to separate dust from non-dust aerosols. We find high model biases of dust extinction in the upper troposphere over the Taklamakan Desert, Gobi Desert, and Tibetan Plateau, especially in the summer (June-July-August, JJA). CESM with dust emission scheme of Kok et al. (2014a, 2014b) has the best agreement with dust extinction profiles and DOD from L15 in the Taklamakan Desert and Tibetan Plateau. CESM with the default dust emission scheme of Zender et al. (2003a) underpredicts DOD in the Tibetan Plateau compared with observations from L15 due to the underestimation of local dust emission. Large uncertainties exist in observations from L15, Y15, and CAL-L3 and have significant impacts on the model evaluation of dust spatial distributions. We also assess dust surface concentrations and 10 m wind speed with meteorological records from weather stations in the Taklamakan and Gobi Deserts during dust events. CESM underestimates dust surface concentrations at most weather stations due to the inability of CESM to capture strong surface wind events.
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http://dx.doi.org/10.1029/2019JD030799DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7340102PMC
July 2019

Factors Causing Abnormal Heart Failure After Successful Fluid Resuscitation on Acute Pancreatitis Patients.

Pancreas 2020 04;49(4):e33-e35

Department of Rehabilitation Medicine The First Affiliated Hospital of Medical College Zhejiang University Hangzhou, China

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http://dx.doi.org/10.1097/MPA.0000000000001532DOI Listing
April 2020

Contrasting effects on deep convective clouds by different types of aerosols.

Nat Commun 2018 09 24;9(1):3874. Epub 2018 Sep 24.

Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, 80309, CO, USA.

Convective clouds produce a significant proportion of the global precipitation and play an important role in the energy and water cycles. We quantify changes of the convective cloud ice mass-weighted altitude centroid (Z) as a function of aerosol optical thickness (AOT). Analyses are conducted in smoke, dust and polluted continental aerosol environments over South America, Central Africa and Southeast Asia, using the latest measurements from the CloudSat and CALIPSO satellites. We find aerosols can inhibit or invigorate convection, depending on aerosol type and concentration. On average, smoke tends to suppress convection and results in lower Z than clean clouds. Polluted continental aerosol tends to invigorate convection and promote higher Z. The dust aerosol effects are regionally dependent and their signs differ from place to place. Moreover, we find that the aerosol inhibition or invigoration effects do not vary monotonically with AOT and the variations depend strongly on aerosol type. Our observational findings indicate that aerosol type is one of the key factors in determining the aerosol effects on convective clouds.
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http://dx.doi.org/10.1038/s41467-018-06280-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6155150PMC
September 2018

Tightening of tropical ascent and high clouds key to precipitation change in a warmer climate.

Nat Commun 2017 06 7;8:15771. Epub 2017 Jun 7.

Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA.

The change of global-mean precipitation under global warming and interannual variability is predominantly controlled by the change of atmospheric longwave radiative cooling. Here we show that tightening of the ascending branch of the Hadley Circulation coupled with a decrease in tropical high cloud fraction is key in modulating precipitation response to surface warming. The magnitude of high cloud shrinkage is a primary contributor to the intermodel spread in the changes of tropical-mean outgoing longwave radiation (OLR) and global-mean precipitation per unit surface warming (dP/dT) for both interannual variability and global warming. Compared to observations, most Coupled Model Inter-comparison Project Phase 5 models underestimate the rates of interannual tropical-mean dOLR/dT and global-mean dP/dT, consistent with the muted tropical high cloud shrinkage. We find that the five models that agree with the observation-based interannual dP/dT all predict dP/dT under global warming higher than the ensemble mean dP/dT from the ∼20 models analysed in this study.
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http://dx.doi.org/10.1038/ncomms15771DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5467267PMC
June 2017

CloudSat 2C-ICE product update with a new parameterization in lidar-only region.

J Geophys Res Atmos 2015 Dec 14;120(23):12198-12208. Epub 2015 Dec 14.

Department of Atmospheric Science University of Utah Salt Lake City Utah USA.

The CloudSat 2C-ICE data product is derived from a synergetic ice cloud retrieval algorithm that takes as input a combination of CloudSat radar reflectivity ( ) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation lidar attenuated backscatter profiles. The algorithm uses a variational method for retrieving profiles of visible extinction coefficient, ice water content, and ice particle effective radius in ice or mixed-phase clouds. Because of the nature of the measurements and to maintain consistency in the algorithm numerics, we choose to parameterize (with appropriately large specification of uncertainty) and lidar attenuated backscatter in the regions of a cirrus layer where only the lidar provides data and where only the radar provides data, respectively. To improve the parameterization in the lidar-only region, the relations among , extinction, and temperature have been more thoroughly investigated using Atmospheric Radiation Measurement long-term millimeter cloud radar and Raman lidar measurements. This parameterization provides a first-order estimation of as a function extinction and temperature in the lidar-only regions of cirrus layers. The effects of this new parameterization have been evaluated for consistency using radiation closure methods where the radiative fluxes derived from retrieved cirrus profiles compare favorably with Clouds and the Earth's Radiant Energy System measurements. Results will be made publicly available for the entire CloudSat record (since 2006) in the most recent product release known as R05.
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http://dx.doi.org/10.1002/2015JD023600DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102169PMC
December 2015

Airborne compact rotational Raman lidar for temperature measurement.

Opt Express 2016 Sep;24(18):A1210-23

We developed an airborne compact rotational Raman lidar (CRL) for use on the University of Wyoming King Air (UWKA) aircraft to obtain two-dimensional (2D) temperature disman tributions. It obtained fine-scale 2D temperature distributions within 3 km below the aircraft for the first time during the PECAN (Plains Elevated Convection At Night) campaign in 2015. The CRL provided nighttime temperature measurements with a random error of <0.5 K within 800 m below aircraft at 45 m vertical and 1000 m horizontal resolution. The temperatures obtained by the CRL and a radiosonde agreed. Along with water vapor and aerosol measurements, the CRL provides critical parameters on the state of the lower atmosphere for a wide range of atmospheric research.
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http://dx.doi.org/10.1364/OE.24.0A1210DOI Listing
September 2016

Vertically resolved separation of dust and other aerosol types by a new lidar depolarization method.

Opt Express 2015 Jun;23(11):14095-107

This paper developed a new retrieval framework of external mixing of the dust and non-dust aerosol to predict the lidar ratio of the external mixing aerosols and to separate the contributions of non-spherical aerosols by using different depolarization ratios among dust, sea salt, smoke, and polluted aerosols. The detailed sensitivity tests and case study with the new method showed that reliable dust information could be retrieved even without prior information about the non-dust aerosol types. This new method is suitable for global dust retrievals with satellite observations, which is critical for better understanding global dust transportation and for model improvements.
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http://dx.doi.org/10.1364/OE.23.014095DOI Listing
June 2015

Compact airborne Raman lidar for profiling aerosol, water vapor and clouds.

Opt Express 2014 Aug;22(17):20613-21

A compact airborne Raman lidar system, which can perform water vapor and aerosol measurements both during nighttime and daytime is described. The system design, setup and the data processing methods are described in the paper. The Raman lidar was tested on University of Wyoming King Air research aircraft (UWKA) during the Wyoming King Air PBL Exploratory Experiment (KAPEE) in 2010. An observation showing clouds, aerosols and a dry line is presented to illustrate the lidar detection capabilities. Comparisons of the water vapor and aerosol measurements using the Raman lidar and other in situ airborne instruments show good agreement.
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http://dx.doi.org/10.1364/OE.22.020613DOI Listing
August 2014

Retrieval of effective complex refractive index from intensive measurements of characteristics of ambient aerosols in the boundary layer.

Opt Express 2013 Jul;21(15):17849-62

Key Laboratory of Atmospheric Composition and Optical Radiation, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.

Aerosol complex refractive index (ACRI) has attracted intensive attentions due to its significance in modeling aerosol radiative effects. Determinations of ACRI from surface measurements of aerosol scattering and absorption coefficients as well as number size distributions during June, 2008 based on an iterative Mie algorithm were performed. The aim of our study was to introduce an inversion approach with the merits of high time-resolutions to retrieve the optically effective ACRI, especially its imaginary part. Based on simultaneous measurements of aerosol characteristics, mean ACRI value of 1.50 ( ± 0.34)-i0.025 ( ± 0.015) at 550 nm in Hefei in summer was deducted. The lower imaginary parts with higher single scattering albedos and lower scattering Angstrom exponents were obtained for haze periods compared with nonhaze conditions with similar air-mass back-trajectories, indicating more large and scattering particles contributing to the formation of haze episodes. The derived imaginary parts of ACRI related to agricultural biomass burning were in the range from 0.013 to 0.029 at 550 nm. Significant negative correlations between retrieved imaginary parts of ACRI and measured single scattering albedos indicate that our retrieval approach is a reasonable method for determining the imaginary parts of complex refractive indices of aerosol particles.
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http://dx.doi.org/10.1364/OE.21.017849DOI Listing
July 2013

Improved calibration method for depolarization lidar measurement.

Authors:
Bo Liu Zhien Wang

Opt Express 2013 Jun;21(12):14583-90

Department of Atmospheric Science, University of Wyoming, Laramie, WY 82071, USA.

An improved calibration method for lidar depolarization measurement is described. With this method the system constants including the electronic gain ratio of the parallel and perpendicular channels, the optical reflectance and transmission parameters of the polarizing beam splitter, and the linear polarization ratio of the emitting laser beam can be determined conveniently by using lidar measurements with a half-wave plate oriented at selected angles.
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http://dx.doi.org/10.1364/OE.21.014583DOI Listing
June 2013

Formation and spread of aircraft-induced holes in clouds.

Science 2011 Jul;333(6038):77-81

National Center for Atmospheric Research (NCAR), Boulder, CO 80301, USA.

Hole-punch and canal clouds have been observed for more than 50 years, but the mechanisms of formation, development, duration, and thus the extent of their effect have largely been ignored. The holes have been associated with inadvertent seeding of clouds with ice particles generated by aircraft, produced through spontaneous freezing of cloud droplets in air cooled as it flows around aircraft propeller tips or over jet aircraft wings. Model simulations indicate that the growth of the ice particles can induce vertical motions with a duration of 1 hour or more, a process that expands the holes and canals in clouds. Global effects are minimal, but regionally near major airports, additional precipitation can be induced.
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http://dx.doi.org/10.1126/science.1202851DOI Listing
July 2011

Wyoming Cloud Lidar: instrument description and applications.

Opt Express 2009 Aug;17(16):13576-87

Department of Atmospheric Science, University of Wyoming, Laramie, Wyoming, USA.

The Wyoming Cloud Lidar (WCL), a compact two-channel elastic lidar, was designed to obtain cloud measurements together with the Wyoming Cloud Radar (WCR) on the University of Wyoming King Air and the National Science Foundation/National Center of Atmospheric Research C-130 aircraft. The WCL has been deployed in four field projects under a variety of atmospheric and cloud conditions during the last two years. Throughout these campaigns, it has exhibited the needed reliability for turn-key operation from aircraft. We provide here an overview of the instrument and examples to illustrate the measurements capability of the WCL. Although the WCL as a standalone instrument can provide unique measurements for cloud and boundary layer aerosol studies, the synergy of WCL and WCR measurements coupled with in situ sampling from an aircraft provide a significant step forward in our ability to observe and understand cloud microphysical property evolution.
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http://dx.doi.org/10.1364/oe.17.013576DOI Listing
August 2009

Innate immune responses in peptidoglycan recognition protein L-deficient mice.

Mol Cell Biol 2004 Sep;24(18):7949-57

Howard Hughes Medical Institute, Department of Medicine, University of California San Francisco, 94143-0654, USA.

Peptidoglycan recognition proteins (PGRPs) constitute a family of innate immune recognition molecules. In Drosophila, distinct PGRPs bind to peptidoglycans on gram-positive or gram-negative bacteria and provide essential signals upstream of the Toll and Imd pathways required for immunity against infection. Four PGRPs, PGRP-L, -S, -Ialpha, and -Ibeta, are expressed from three genes in mammals. In this paper, we provide direct evidence that the longest family member, PGRP-L, is a secreted serum protein with the capacity to multimerize. Using gene targeting to create PGRP-L-deficient mice, we demonstrate little contribution by PGRP-L to systemic challenge using gram-negative bacteria (Escherichia coli, slightly less susceptible), Gram-positive bacteria (Staphylococcus aureus), or yeast (Candida albicans). Peritoneal macrophages from PGRP-L-deficient mice produced decreased amounts of the inflammatory cytokines interleukin 6 and tumor necrosis factor alpha when stimulated with E. coli or lipopolysaccharide, but comparable amounts when stimulated with S. aureus, C. albicans, or their cell wall components. Additionally, these cells produced similar amounts of cytokines when challenged with gram-positive or -negative peptidoglycans. In contrast to its critical role in immunity in flies, PGRP-L is largely dispensable for mammalian immunity against bacteria and fungi.
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http://dx.doi.org/10.1128/MCB.24.18.7949-7957.2004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC515053PMC
September 2004